He is doing it to raise money for two charities.
His final ultra marathon was in York, England.
The legendary miler gives his full backing of the record attempt.
Man Completes Marathon In London's "Eye"
He hopes to break the bomb-disposal-gear marathon world record.
He got the idea from former New York Giants wide receiver Armani Toomer.
It's an 11,000-mile journey to benefit the Red Cross.
He once ran across the Sahara Desert for charity.